| Issue | Fix Version | Assignee | Priority | Status | Resolution | Resolved In Build |
|---|---|---|---|---|---|---|
| JDK-2176733 | 7 | Yumin Qi | P3 | Closed | Fixed | b03 |
| JDK-2171795 | 6u4 | Yumin Qi | P3 | Resolved | Fixed | b03 |
java.lang.Integer implements 32-bit rotation as:
public static int rotateLeft(int i, int distance) {
return (i << distance) | (i >>> -distance);
}
public static int rotateRight(int i, int distance) {
return (i >>> distance) | (i << -distance);
}
x86 includes the ROL and ROR instruction that do just that, but HotSpot currently does not take advantage of them. Note that in many use cases, distance is a compile-time constant.
Similarly for Long.rotateLeft() and Long.rotateRight().
public static int rotateLeft(int i, int distance) {
return (i << distance) | (i >>> -distance);
}
public static int rotateRight(int i, int distance) {
return (i >>> distance) | (i << -distance);
}
x86 includes the ROL and ROR instruction that do just that, but HotSpot currently does not take advantage of them. Note that in many use cases, distance is a compile-time constant.
Similarly for Long.rotateLeft() and Long.rotateRight().
- backported by
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JDK-2171795 Optimize Integer.rotateLeft()
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- Resolved
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-
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- Closed
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- relates to
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JDK-6431242 Optimize Integer.reverseBytes()
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- Resolved
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